Overexpression Of Fibrinogen-like Protein 2 Downregulated The Expression Of Programmed Cell Death-1,Decreased Cardiac Function In Autoimmune Myocarditis Rats And The Molecular Mechanism Involved

Objective:The aim of this study was to establish the model of experimental autoimmune myocarditis in rats. Thread detect the level of PD-1 in rats with autoimmune myocarditis, discuss its significance in the development of autoimmune myocarditis?Evaluate the effect of lentivirus vector mediated transfer of fgl2 gene overexpression on immuno-inflammation-mediate cardiac function and determine if Fgl2 overexpression can affect the expression of PD-1 in experimental autoimmune myocarditis.Methods:Thirty-two male Lewis rats were randomly divided into the normal control(NC)group(n = 8) and the experimental autoimmune myocarditis group(EAM group)(n =24). EAM was induced in Lewis rats by injection of porcine cardiac myosin on day 1and day 8. The immunized rats were divided into three groups. The Fgl2 overexpression autoimmune myocarditis group(EAM-Fgl2 group)(n=8)received the lentivirus containing fgl2 on day 1. The green fluorescent protein group(EAM-GFP group) received the lentivirus containing GFP as the control lentivirus. Other eight rats was the autoimmune myocarditis group(EAM group). On day 40, all rats were euthanized after echocardiography and histopathologically examined for the degree of inflammatory reaction. Western blotting was performed to detect fibrinogen-like protein 2(Fgl2), programmed death-1(PD-1), forkhead transcription factor 3(Foxp3),retinoic acid-related orphan receptor(ROR?t) expression, and real-time PCR was performed to detect Fgl2, PD-1, ROR?t and Foxp3 expression. ELISA was applied to detect interleukin(IL)-6, interleukin(IL)-17, interferon(IFN)-? and B-type natriuretic peptide(BNP) cytokine production.Results:On day 40, cardiac function and myocardium inflammatory injury deteriorate in the experimental autoimmune myocarditis group compared to the NC group(p<0.05).The level of IL-17, IL-6, IFN-? and BNP cytokine production in serum in EAM group was higher than those in NC group(p<0.05). The expression of Fgl2, Foxp3, ROR?t protein and m RNA was statistically upper in the EAM groups compared to the NC group(p<0.05). However PD-1 protein and m RNA expression showed a contrary tendency and the differences were also significant(P<0.05). And there was significant alteration in the EAM-Fgl2 group(p<0.05).Conclusion:Repetitively immunized with porcine cardiac myosin was capable of inducing experimental autoimmune myocarditis. Fgl2 significantly augmented Th17 cell and IL-17 cytokine production. The overexpression of Fgl2 co-stimulatory pathway with PD-1 aggravated autoimmune inflammation-mediated cardiac remodeling and decreased cardiac function.